Sheet collecting apparatus and sheet collecting method

ABSTRACT

In a sheet collecting apparatus having a collecting table on which a sheet charged by a charging means is collected, a suctioning/transporting means for suctioning and transporting the sheet charged by the charging means along a charging direction and releasing the sheet above the collecting table, back stoppers for receiving the sheet transported by the suctioning/transporting means downstream of the collecting table along a transport direction of the sheet, and a back guide disposed downstream of the collecting table along the transport direction of the sheet for regulating a position along the transport direction of the sheet received by the back stoppers, the sheet collecting apparatus positions the sheet charged by the charging means at a predetermined position and stacks it in a layer state.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese PatentApplication No. 2008-048522, the disclosures of which is incorporated byreference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet collecting apparatus and asheet collecting method.

2. Description of the Related Art

As disclosed in Japanese Patent Application Laid-Open (JP-A) No.2006-327713, there is a sheet collecting apparatus which has a backstopper for receiving a sheet charged by a charging means downstream ofa collecting table and a sheet holding means for receiving the sheetabove the collecting table, releases the sheet after it is received bythe sheet holding means from the below, and drops the sheet onto thecollecting table as a sheet collecting apparatus for collecting anplanographic printing plate like a computer-to-plate (CTP) printingplate which has no slip sheet placed on the printing surface thereof andof which printing surface is liable to be scratched.

However, when the CTP printing surface is charged at a higher speed, theCTP printing surface may flutter because the kinetic energy of thecharged CTP printing surface is not sufficiently absorbed by the backstopper. In this case, since the sheet holding means must wait whileholding the CTP printing surface until fluttering of it is ceased, apitch at which the CTP printing surface is collected cannot be increasedso much.

If the CTP printing surface being held is released before flutteringthereof caused by the collision thereof against the back stopper is notcompletely ceased, since the CTP printing surface is collected on thecollecting table before the kinetic energy is not completely released,there is a possibility that not only the CTP printing surface is notsecurely positioned on the sheet collecting table but also a scratch isgenerated to the periphery of the CTP printing surface.

SUMMARY OF THE INVENTION

An object of the invention, which was made to solve the above problem,is to provide a sheet collecting apparatus which does not generate adamage such as a scratch and the like on the sheet surface of a sheetsuch as a CTP printing plate of which surface is liable to be scratchedeven if the sheet is charged at a high charge speed without a protectionmember such as slip sheet at a high collection pitch.

A first aspect for solving the above problem relates to a sheetcollecting apparatus for positioning a sheet charged by charging meansat a predetermined position and stacking it in a layer state comprising:a collecting table on which the sheet charged by the charging means arecollected; a suctioning/transporting means for suctioning andtransporting the sheet charged by the charging means along a chargingdirection and releasing the sheet above the collecting table; backstoppers for receiving the sheet transported by thesuctioning/transporting means downstream of the collecting table along atransport direction of the sheet; and a back guide disposed downstreamof the collecting table along the transport direction of the sheet forregulating a position along the transport direction of the sheetreceived by the back stoppers.

In the sheet collecting apparatus of the first aspect, a sheet chargedby the charging means is sucked and transported above the collectingtable by the suctioning/transporting means and released therefrom abovethe collecting table.

Since the sheet released from the suctioning/transporting means isreceived by the back stoppers and the kinetic energy thereof is absorbedthereby, occurrence of fluttering of the sheet can be prevented. Thesheet received by the back stoppers is collected on the collecting tablein a state that the downstream side of the sheet in the chargingdirection is positioned by the back guide.

A second aspect for solving the above problem relates to the sheetcollecting apparatus according to the first aspect having a pair of sideguide members for regulating a charge path of the sheet transported bythe suctioning/transporting means and released from thesuctioning/transporting means above the collecting table.

In the sheet collecting apparatus of the second aspect, the sheetreleased from the suctioning/transporting means above the collectingtable is received by the back stoppers in a state that the two sides ofthe sheet along the charging direction are positioned by the side guidemembers and collected on the collecting table in a state that thedownstream side of the sheet in the charging direction is positioned bythe back guide. Therefore, the sheet is collected in the state that thethree sides in total of the sheet, i.e., the two sides along thecharging direction and the downstream side in the charging direction arepositioned.

According to the sheet collecting apparatus of the second aspect, thecharged sheet is collected on the collecting table in the state that thethree sides thereof are positioned by the side guide members and theback guide member as described above. Therefore, disturbance of a sheeton the collecting table can be more effectively reduced than a sheetcollecting apparatus having no side guide members.

A third aspect for solving the above problem relates to the sheetcollecting apparatus according to the second aspect including edgesupport members disposed so that they can appear or disappear from theside guide members and receiving the sheet from the below by projectingfrom the side guide members when the sheet is released from thesuctioning/transporting means.

In the sheet collecting apparatus of the third aspect, when a sheet isreleased from the suctioning/transporting means, the edge supportmembers project from the side guide members and hold the sheet from thebelow. By this operation, the sheet is dropped onto the collecting tablein a state that the drop energy of the sheet is almost absorbed.

According to the third aspect, the sheet released from thesuctioning/transporting means is held by the edge support members fromthe below and dropped onto the collecting table in the state that thedrop energy thereof is almost absorbed as described above. Therefore,occurrence of a damage such as a scratch and the like on a sheet surfacecan be more effectively suppressed than a sheet collecting apparatushaving no edge support members.

A fourth aspect for solving the above problem relates to the sheetcollecting apparatus according to any of the first to third aspectscomprising a front stopper disposed opposite to the back stoppers andthe back guide member across the collecting table.

In the sheet collecting apparatus of the fourth aspect, a sheet releasedfrom the suctioning/transporting means above the collecting table isreceived by the back stoppers in a state that the two sides of the sheetalong the charging direction are positioned by the side guide membersand collected on the collecting table in a state that the side of thesheet downstream of a charge side is positioned by the back guide andthe side of the sheet upstream in the charging direction is positionedby the front stopper.

According to the fourth aspect, the charged sheet is collected on thecollecting table in the state that the four sides of the sheet, i.e.,the two sides along the charging direction and the two sides downstreamand upstream in the charging direction are positioned. Therefore,disturbance of a sheet bundle on the collecting table can be moreeffectively reduced than a sheet collecting apparatus having no frontstopper.

A fifth aspect for achieving the above object relates to the sheetcollecting apparatus according to any of the first to fourth aspectswherein the suctioning/transporting means include a breathable suctionbelt rotating in a predetermined direction and suction boxes disposedinside the suction belt for suctioning the sheet on the front surface ofthe suction belt by suctioning air through the suction belt.

In the sheet collecting apparatus of the fifth aspect, by suctioning theair in the suction boxes while rotating the suction belt so that thesurface thereof facing the collecting table moves in the same directionas the charging direction a sheet charged by the charging means issucked onto the outer surface of the suction conveyer and moved alongthe charging direction of the sheet. When the sheet moves above thecollecting table, the sheet can be released from the front surface ofthe suction conveyer and dropped downward by supplying air into thesuction boxes.

According to the fifth aspect, a timing at which a sheet is releasedfrom the suction conveyer can be set by setting timing at which apressure reduced state is disrupted by supplying air into the suctionboxes. Therefore, there is provided a sheet collecting apparatus whereintiming at which a charged sheet is released toward the collecting tablecan be easily set.

A sixth aspect for achieving the above object relates to the sheetcollecting apparatus according to any of the first to fifth aspectswherein the back guide member is formed so as to have a sheet receivingheight that is a height for receiving the sheet set higher than thelower edges of the back stoppers.

In the sheet collecting apparatus of the sixth aspect, since the sideguide member is formed so that the sheet receiving height of the backguide is higher than the lower edges of the back stoppers, the sheetreleased from the suctioning/transporting means won't pass under thelower edges of the back stoppers because the height is regulated by theback guide.

According to the sixth aspect, a sheet released from thesuctioning/transporting means is received at a position higher than thelower edges of the back stoppers in the back guide as described above.Therefore, the front edge of a sheet is effectively prevented fromentering between the back stoppers and the back guide.

A seventh aspect for achieving the above object relates to the sheetcollecting apparatus according to any of the second to sixth aspectswherein a sheet receiving height as a height for receiving the sheet bythe back guide member is lower than a positioning height for positioningthe sheet by the side guide members and the front stopper in.

In the sheet collecting apparatus of the seventh aspect, the sheetreceiving height, which is the height in which a sheet is received bythe back guide member, is lower than the position determination heightin which the sheet is positioned by the side guides and the frontstopper. Therefore, a sheet released from the suctioning/transportingmeans is at first received by the back stopper and is moved to the frontstopper side. The upstream side of the sheet in the transport directionthereof is positioned by being butted against the portions of thepositioning height of the side guides and then the two sides of thesheet along the transport direction are positioned by being buttedagainst the portions of the side guides located at the positioningheight thereof. Finally, the downstream side of the sheet in thetransport direction is positioned by being butted against the portion ofthe side guide member located at the sheet receiving height thereof.

According to the seventh aspect, as described above, a sheet releasedfrom the suctioning/transporting means is positioned in the sequence ofthe side guides, the front stopper, and the back guide and finallycollected on the collecting table in the state that all the four sidesthereof are positioned. Therefore, since when the sheets are droppedafter being held by the edge support member from the below, disturbanceof sheets on the collecting table are more effectively suppressed, itcan be more effectively prevented that the sheets are scratched by beingrubbed with each other when they are dropped onto a collecting surface.

An eighth aspect for achieving the above object relates to the sheetcollecting apparatus according to any of the first to seventh aspectshaving an auxiliary air nozzle that is disposed below the inlet sideedge of the suctioning/transporting means from which the sheets arecharged so as to lift the sheet sucked and transported by thesuctioning/transporting means upward by jetting air upward.

In the sheet collecting apparatus of the eight aspect, a charged sheetcan be pressed against the suctioning/transporting means by jetting airfrom the auxiliary air nozzle to the sheet.

According to the eighth aspect, since a charged sheet is caused to comeinto intimate contact with the suctioning/transporting means by jettingair from the auxiliary air nozzle, the sheet can be securely sucked tothe suctioning/transporting means even if it is curved in the chargingdirection or a width direction.

A ninth aspect for achieving the above object relates to the sheetcollecting apparatus according to any of the fourth to eighth aspectswherein the front stopper is formed such that the position thereof canbe changed according to the measurement of a sheet to be charged in thecharging direction thereof.

In the sheet collecting apparatus of the ninth aspect, when a sheethaving a larger measurement in the charging direction is collected thefront stopper is moved farther away from the back stoppers than in acase when a sheet having a smaller measurement in the charging directionis collected.

According to the ninth aspect, since the position of the front stopperis adjusted according to the measurement of a sheet in the chargingdirection, the relative positional relation of the sheet to the backstoppers when the sheet is released from the suctioning/transportingmeans can be kept constant at a time when a sheet having a largemeasurement in the charging direction is collected or at a time when asheet having a small measurement in the charging direction is collected.Therefore, since a sheet can be collected while keeping a sheetseparating condition in the suctioning/transporting means and timing atwhich the sheet is held from the below constant, a damage of the sheetdue to disturbance of a sheet surface can be particularly effectivelyprevented.

A tenth aspect for achieving the above object relates to a method ofcollecting a sheet charged by a charging means along a predetermineddirection in a layer state on a collecting table of a sheet collectingapparatus which has the collecting table, a suctioning/transportingmeans disposed above the collecting table, back stoppers disposeddownstream of the collecting table along a transport direction of thesheets, and a back guide member disposed downstream of the collectingtable along the transport direction of the sheet adjacent to the backstoppers, the method comprising a step of suctioning by thesuctioning/transporting means the sheet charged by the charging means,transporting the sheet along the charging direction of the sheets, andreleasing the sheet above the collecting table, a step of receiving thesheet released from the suctioning/transporting means downstream of thecollecting table along the transport direction of the sheet by the backstoppers, and a step of regulating a position along the transportdirection of the sheet, which is received by the back stoppers, by theback guide member.

In the sheet collecting method of the tenth aspect, a sheet charged bythe charging means is sucked and transported above the collecting tableby the suctioning/transporting means and released from thesuctioning/transporting means above the collecting table.

Since the sheet released from the suctioning/transporting means isreceived by the back stoppers and the kinetic energy thereof is absorbedthereby, occurrence of fluttering of the sheet can be prevented. Thesheet received by the back stoppers is collected on the collecting tableby that the downstream side of the sheet in the charging direction ispositioned by the back guide.

In the sheet collecting method of the tenth aspect, a sheet charged asdescribed above is sucked and transported by the suctioning/transportingmeans, released therefrom above the collecting table, and collected onthe collecting table while being positioned by the back guide after itis received by the back stoppers and the kinetic energy thereof isabsorbed.

Accordingly, there can be provided a sheet collecting apparatus whichcan collect a sheet at a high collection pitch without causing a damagesuch as a scratch and the like on a sheet surface even when a sheetwhose surface is liable to be damaged is collected without a protectionmember such as a slip sheet and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an overall arrangement of a sheetcollecting apparatus according to a first exemplary embodiment.

FIG. 2 is a schematic plan view showing a relative positional relationamong side guide members, edge support members, and back guide plates inthe sheet collecting apparatus according to the first exemplaryembodiment.

FIG. 3 is a schematic sectional view showing a relative positionalrelation when a collecting table, the side guide members, the edgesupport members, back stoppers, a front stopper, and a suction belt inthe sheet collecting member according to the first exemplary embodimentare viewed from the side surfaces of them.

FIG. 4 is an enlarged view showing a detailed arrangement of suctionconveyers in the sheet collecting apparatus according to the firstexemplary embodiment.

FIG. 5 is an enlarged view showing another example of the suctionconveyers in the sheet collecting apparatus according to the firstexemplary embodiment.

FIG. 6 is an enlarged view showing still another example of the suctionconveyers in the sheet collecting apparatus according to the firstexemplary embodiment.

FIG. 7 is a partial sectional view showing a mechanism for causing theedge support members to appear or disappear with respect to the sideguide members when it is viewed from above it.

FIG. 8 is a partial sectional view showing the mechanism for causing theedge support members to appear or disappear with respect to the sideguide members when it is viewed from a side thereof.

FIG. 9 is a partial sectional view showing the mechanism for causing theedge support members to appear or disappear with respect to the sideguide members when it is viewed forward of a direction in which anplanographic printing plate is charged.

FIG. 10 is an enlarged sectional view showing a detailed arrangement ofthe back stoppers.

FIG. 11 is an explanatory view showing an operation of the sheetcollecting apparatus according to the first exemplary embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 1. Exemplary Embodiment 1

An example of a sheet collecting apparatus of the present invention willbe explained below.

[Arrangement]

As shown in FIG. 1, the sheet collecting apparatus 100 according to theexemplary embodiment 1 has a pair of back stoppers 4 for receiving anplanographic printing plate P, which is charged by a belt conveyor 200along the direction of an arrow ‘a’, by the front edges thereof, acollecting table 2 which is disposed upstream of the back stoppers 4with respect to the charging direction ‘a’ of the planographic printingplate P, on which the planographic printing plate P received by the backstoppers 4 is collected, and which can be moved upward and downward by alifter (not shown), a front stopper 6 located opposite to the backstoppers 4 across the collecting table 2, and a pair of side guidemembers 8 which are disposed on both the side edges of the collectingtable 2 along the charging direction ‘a’ and guide the planographicprinting plate P charged onto the collecting table 2 from both the sidesthereof.

The sheet collecting apparatus 100 further has back guide plates 1 as anexample of a back guide member of the invention. The back guide plates 1are disposed at positions where they confront the front stopper 6 acrossthe collecting table 2 on both the sides of the back stoppers 4 whenviewed from the charging direction ‘a’. The planographic printing plateP is an example of a sheet collected on the sheet collecting apparatusof the invention and placed on the uppermost surface of an planographicprinting plate bundle 50 which has been collected on the collectingtable 2, i, e., on a sheet collecting surface 51.

A pair of suction conveyers 10 are disposed in the vicinity of sideguide members 8 located above the collecting table 2.

Further, as shown in FIG. 3, an auxiliary air nozzle 7 is disposedupstream of the front stopper 6 with respect to the charging direction‘a’ to eject air upward.

As shown in FIGS. 1 and 2, each of the side guide members 8 has avertical portion 8A that is orthogonal to a collection surface 2A of thecollecting table 2 on which the planographic printing plate P iscollected and a tilt portion 8B extending upward of the vertical portion8A and tilting to the outside. The distance between the right and leftside guide members 8 is preferably 0.2 to 1 mm larger than themeasurement of the planographic printing plate P in the width directionthereof, i.e., the measurement thereof in the direction orthogonal tothe charging direction ‘a’.

The vertical portion 8A of each side guide member 8 has four laterallylong rectangular openings 80 formed therethrough, and edge supportplates 9 are disposed to the openings 80 so as to appear or disappeartherefrom so that they hold the charged planographic printing plate Pfrom the below. As shown in FIG. 2, the edge support plates 9 hold theplanographic printing plate P in the state that they project from theopenings 80. The edge support plates 9 project from the verticalportions 8A preferably in the amount of about 5 to 50 mm. Further, asshown in FIG. 3, a sheet receiving height H₄, which is a height at whichthe edge support plates 9 receive a sheet, is preferably set to about 50mm from the collecting table 2. Further, the distance H₅ from thesuction conveyer 10 to the edge support plates 9 in the height directionthereof is preferably set to about 150 to 200 mm from the viewpoint ofpreventing an planographic printing plate P charged by the suctionconveyer 10 later coming into contact with an planographic printingplate P charged previously.

As shown in FIG. 3, each of the back guide plates 1 is formed so that aheight H_(bg) that is a height from the collecting table 2 to the top ofthe back guide plate 1 is larger than a height H_(bp) that is a heightof the lower edges of the back stoppers 4. The back guide plate 1 has avertical portion 1A orthogonal to the collection surface 2A and a curvedportion 1B disposed on top of the vertical portion 1A and curveddownstream along the charging direction ‘a’.

Further, as shown in FIG. 3, the front stopper 6 also has a verticalportion 6A orthogonal to the collection surface 2A and a curved portion6B located on top of the vertical portion 6A. However, the curvedportion 6B of the front stopper 6 curves upstream in the chargingdirection ‘a’. Note that when the planographic printing plate P, whichis intended to be charged, has a large measurement along the chargingdirection ‘a’, the front stopper 6 can preferably move upstream alongthe charging direction ‘a’, and when the planographic printing plate Phas a small measurement, the front stopper 6 can preferably movedownstream along the charging direction ‘a’.

The back guide plates 1 guide the planographic printing plate P by thecurved portions 1B and receive it by the vertical portions 1A.Accordingly, as shown in FIG. 3, the sheet receiving height H₁ of theback guide plate 1 is the height of the boundary portion between thevertical portion 1A and the curved portion 1B. Likewise, the frontstopper 6 and the side guide members 8 also guide the planographicprinting plate P by the curved portion 6B and the tilt portions 8B andposition it by the vertical portion 6A and the vertical portions 8A.Accordingly, as shown in FIG. 3, the positioning height H₂ of the frontstopper 6 is the height of the boundary between the vertical portion 6Aand the curved portion 6B, and the positioning height H₃ of the sideguide member 8 is the height of the boundary between the verticalportion 8A and the tilt portion 8B.

As shown in FIG. 3, the back side plates 1, the front stopper 6, and theside guide members 8 are formed such that the sheet receiving height H₁of the back guide plates 1 is lower than any of the positioning heightH₂ of the front stopper 6 and the positioning height H₃ of the sideguide members 8 and the positioning height H₃ of the side guide members8 is lower than the positioning height H₂ the front stopper 6. Note thatthe distance from the front stopper 6 to the back guide plates 1 ispreferably about 0.05 to 1 mm larger than the measurement of theplanographic printing plate P along the charging direction ‘a’.

The back guide plate 1 is composed of a metal sheet by which thevertical portion 1A and the curved portion 1B are constitutedintegrally. However, the curved portion 1B may be formed of a resinmaterial of various resins, an elastomer material such as vulcanized gumor non-vulcanized gum, or a soft material such as a soft vinyl chlorideresin in place of that it is formed of metal, and it may be covered withthe soft material. When the curved portion 1B is formed of or coveredwith the resin material and the soft material, it can more effectivelyprevent that the planographic printing plate P is damaged by coming intocontact with the back guide plate 1 as compared with the case that thecurved portion 1B is composed of the metal sheet and conveyed.

The front stopper 6 is composed of a metal sheet which has a curvedupper edge and forms the vertical portion 6A and the curved portion 6Bintegrally.

As shown in FIGS. 1 and 4, the suction conveyer 10 has a suction belt11, which is an endless belt having a lot of suction holes 11A formed onthe entire surface thereof, a pair of drive rollers 12 around which thesuction belt 11 is stretched and which drives the suction belt 11, andsuction boxes 13 disposed in a row inside the suction belt 11. Thesuction belt 11 is stretched such that the inner surface thereof slideson the lower surfaces of the suction boxes 13, and a predeterminednumber of communication holes are formed on the lower surfaces of thesuction boxes 13.

As shown in FIG. 4, the suction boxes 13 has a suction line 15 connectedthereto for suctioning air from inside thereof and a discharging line 16connected thereto for supplying air therein. The suction line 15 isnormally opened, while the discharging line 16 is opened only at a timewhen supplying air into the suction boxes 13. By closing the dischargingline 16 and suctioning air inside the suction boxes 13 through thesuction line 15, the pressure inside the suction box is reduced to areduced pressure or to vacuum, the planographic printing plate P issucked onto the suction belt 11. On the contrary, the planographicprinting plate P is released by supplying air into the suction boxes 13by opening the discharging line 16 while opening the suction line 15 soas to break the vacuum inside the suction boxes 13.

Note that, in addition to the example shown in FIG. 4, as shown in FIG.5, the suction conveyer 10 includes an embodiment wherein the suctionboxes 13 and discharging boxes 14 are alternately arranged inside thesuction belt 11, and the suction line 15 may be connected to the suctionboxes 13 and the discharging line 16 is connected to the dischargingboxes 14. Further, as shown in FIG. 6, the suction line 15 and thedischarging line 16 may be connected to some of the suction boxes 13,for example, the two suction boxes 13 on the upstream side with respectto the charging direction ‘a’ and only the suction line 15 may beconnected to the remaining suction boxes 13. Note that, in the aboveaspects, a predetermined number of discharge holes are formed also tothe lower surfaces of the discharging boxes 14, and the inner surface ofthe suction belt 11 slides on the lower surfaces.

When the planographic printing plate P is sucked, the insides of thesuction boxes 13 are made to a pressure-reduced state or to a vacuumstate by closing the discharging line 16 and discharging the air in thesuction boxes 13 through the suction line 15 in any of the aspects shownin FIGS. 5 and 6. In contrast, the planographic printing plate P isreleased from the front surface of the suction belt 11 by supplying airto the discharging boxes 14 by opening the discharging line 16 andpressurizing the insides of the discharging boxes 14. Note that when theplanographic printing plate P is released in the aspect shown in FIG. 6,the pressure-reduced state or the vacuum state in the discharging boxes14 is disrupted by supplying air into the discharging boxes 14 as wellas supplying air from the discharging line 16 into the two suction boxes13 on the upstream side with respect to the charging direction ‘a’ atthe same time.

The height from the collection surface 2A of the collecting table 2 tothe suction conveyer 10 is set preferably in the range of 200 to 250 mmto prevent an planographic printing plate P charged later frominterfering with an planographic printing plate P charged previously andfell along the back guide plates 1.

As shown in FIGS. 1 and 7 to 9, the mechanism for causing the edgesupport plates 9 to appear or disappear from the side guide members 8has a shaft 20 disposed outside the vertical portions 8A of the sideguide members 8 with respect to the collecting table 2, a motor 21 forrotating the shaft 20, and speed reduction gears 23, 22 for transmittingthe rotation of the motor 21 to the shaft 20. The edge support plates 9are fixed to the shaft 20 along the longitudinal direction thereof. Whenthe motor 21 rotates, the shaft 20 is also rotated, thereby the edgesupport plates 9 also rotate about the axial line of the shaft 20. Withthis operation, the edge support plates 9 project from the side guidemembers 8 toward the collecting table 2 as shown by a solid line in FIG.9 and retracted outside the side guide members 8 as shown by adouble-dashed line.

As shown in FIG. 10, each of the back stoppers 4 has a back stopperplate 40 which is in contact with the charged planographic printingplate P and a shock absorber device 43 for absorbing a shock along thecharging direction ‘a’ of the back stopper plate 40.

As shown in, for example, Japanese Patent Application Laid-Open (JP-A)No. 8-290860, the shock absorber device 43 has a first shock absorbingmechanism 41 for absorbing shock caused when the planographic printingplate P falling along the charging direction ‘a’ is abutted against theback stopper plates 40 and a second shock absorbing mechanism 42continuously disposed to the first shock absorbing mechanism 41 forabsorbing reaction force caused by the first shock absorbing mechanism41 returning toward upstream with respect to the charging direction ‘a’.

The first shock absorbing mechanism 41 is composed of a spline shaft 41Ato which the back stopper plate 40 is fixed, a moving cylinder 41Bpositioned outside the spline shaft 41A, a ball holder 41C disposedinside the moving cylinder 41B and holding the spline shaft 41A so thatit advances and retracts upstream and downstream with respect to thecharging direction ‘a’, and a coil spring 41D interposed between theback stopper plate 40 and the moving cylinder 41B and urging the backstopper plate 40 upstream with respect to the charging direction ‘a’.

In contrast, the second shock absorbing mechanism 42 has a fixedexternal cylinder 42A, a ball holder 42B holding the moving cylinder 41Binside the fixed external cylinder 42A so that it advances and retractsupstream and downstream with respect to the charging direction ‘a’, anda coil spring 42C urging the moving cylinder 41B upstream with respectto the charging direction ‘a’.

The coil spring 42C has a spring constant larger than that of the coilspring 41D. Accordingly, the inertia received by the back stopper plate40 is at first absorbed by the coil spring 41D. Then, the reaction forcecaused by the first shock absorbing mechanism 41 when returning to theoriginal position thereof is absorbed by the coil spring 42C.

Note that the measurement or position of the back stoppers 4 as well asthe back guide plate 1 can be changed in accordance with the measurementof the planographic printing plate P to be charged along the chargingdirection ‘a’ thereof. Specifically, when the planographic printingplate P having a small measurement along the charging direction ‘a’ ischarged, the back stoppers 4 and the back guide plates 1 are positionednear to the front stopper 6, whereas when the planographic printingplate P having a large measurement along the charging direction ‘a’ ischarged, the back stoppers 4 and the back guide plates 1 are positionedaway from the front stopper 6.

[Operation]

An operation of the sheet collecting apparatus 100 will be explainedbelow.

First, the collecting table 2 is moved upward by a lifter (not shown).

When the collecting table 2 is moved upward to a predetermined height,the belt conveyor 200 charges the planographic printing plate P alongthe charging direction ‘a’. At the time when the planographic printingplate P is charged, air is jetted toward the planographic printing plateP from the auxiliary air nozzle 7 and the planographic printing plate Pis lifted toward the suction conveyer 10.

The charged planographic printing plate P is sucked by the suctionconveyer 10 and transported along the charging direction ‘a’. When theplanographic printing plate P is transported over the collecting table2, suction of the planographic printing plate P onto the suctionconveyer 10 is released by supplying air into the suction boxes 13 tobreak the reduced pressure or vacuum state therein or by supplying airinto the discharging box 14 so that the planographic printing plate isreleased from the suction belt 11 as shown by P₁ in FIG. 11.

When the planographic printing plate P is released from the suction belt11, the upstream one side of the planographic printing plate P is guidedfirst by the front stopper 6 with respect to the charging direction ‘a’,and next the two sides of the planographic printing plate P along thecharging direction ‘a’ are guided by the side guide members 8 as well asthe planographic printing plate P is received by the upper edge of theback guide plates 1 and by the approximate central portions of the backstopper plates 40 in the back stoppers 4 as shown by P2 in FIG. 11.

When the back stopper plate 40 receives and stops the planographicprinting plate P, the shock received by the back stopper 40 is absorbedby the shock absorber device 43 as described below.

First, as shown by a solid line in FIG. 11, the back stopper 4 is moveddownstream along the charging direction ‘a’ by the shock from theplanographic printing plate P. As a result, the coil spring 41D of thefirst shock absorbing mechanism 41 is contracted. Next, the force ofextending the coil spring 41D causes to move the moving cylinder 41Bdownstream along the charging direction ‘a’. However, since the movingcylinder 41B is urged upstream with respect to the charging direction‘a’ by the coil spring 42C of the second shock absorbing mechanism 42and moreover the coil spring 42C has the spring constant larger thanthat of the coil spring 41D, the moving cylinder 41B is returned to anoriginal position by the urging force of the coil spring 42C. As aresult, although the back stopper plate 40 also receives force forcausing it to return upstream with respect to the charging direction ‘a’as shown by a double-dashed line in FIG. 11, the force is absorbed bythe coil spring 41D.

Accordingly, although the planographic printing plate P is pushed backtoward the front stopper 6 as shown by P₃ in FIG. 11, since force ofpushing back the planographic printing plate P is caused by the coilspring 41D having a small spring constant, the planographic printingplate P is not pushed back toward the front stopper 6 by a large amountof force.

As described above, in the sheet collecting apparatus 100 of theexemplary embodiment 1, by disposing the back guide plates 1, the backstoppers 4 can be employed only for absorbing shock. Thus, the springreaction in the back stoppers 4 is reduced as much as possible byarranging them as described above so that the force for pushing andreturning the planographic printing plate P toward the front stopper 6can be reduced as much as possible.

Then, the final one side, i.e., the downstream side of the planographicprinting plate P is guided along the charging direction ‘a’ by the backguide plate 1 as well as the planographic printing plate P is receivedby the edge support plates 9 from the downstream side thereof as shownby P3 in FIG. 11.

When the planographic printing plate P is received by the edge supportplates 9, it is dropped onto the collecting table 2 by pulling the edgesupport plates 9 to the outsides of the side guide members 8.

When the sheet collecting apparatus 100 is used as described above, notonly planographic printing plates P can be collected but also a shock ina height direction, which is generated when a new planographic printingplate is dropped onto the collecting table 2 or onto the sheetcollecting surface 51, can be absorbed in a state that a movement in adirection along the charging direction ‘a’ is almost eliminated betweenthe collecting table 2 or the planographic printing plate P, which isalready collected onto the collecting table 2 and forms the sheetcollecting surface 51, and a newly charged planographic printing plateP. Accordingly, even if an planographic printing plate such as CTP whoseprinting layer is liable to be damaged can be collected without a slipsheet.

1. A sheet collecting apparatus for positioning a sheet charged by acharging means at a predetermined position and stacking it in a layerstate; the sheet collecting apparatus comprising: a collecting table onwhich the sheet charged by the charging means is collected; asuctioning/transporting means for suctioning and transporting the sheetcharged by the charging means along a charging direction and releasingthe sheet above the collecting table; back stoppers for receiving thesheet transported by the suctioning/transporting means downstream of thecollecting table along a transport direction of the sheet; and a backguide disposed downstream of the collecting table along the transportdirection of the sheet for regulating a position along the transportdirection of the sheet received by the back stoppers.
 2. The sheetcollecting apparatus of claim 1, comprising a pair of side guide membersfor regulating a charge path of the sheet transported by thesuctioning/transporting means and released from thesuctioning/transporting means above the collecting table.
 3. The sheetcollecting apparatus of claim 2, comprising edge support membersdisposed so that they can appear or disappear from the side guidemembers and receiving the sheet from under them by projecting from theside guide members when the sheet is released from thesuctioning/transporting means.
 4. The sheet collecting apparatus ofclaim 1, comprising a front stopper disposed opposite to the backstoppers and to a back guide member across the collecting table.
 5. Thesheet collecting apparatus of claim 2, comprising a front stopperdisposed opposite to the back stoppers and to a back guide member acrossthe collecting table.
 6. The sheet collecting apparatus of claim 3,comprising a front stopper disposed opposite to the back stoppers and toa back guide member across the collecting table.
 7. The sheet collectingapparatus of claim 1, wherein the suctioning/transporting means is asuction conveyer comprising a breathable suction belt rotating in apredetermined direction and suction boxes disposed inside the suctionbelt for suctioning the sheet onto the front surface of the suction beltby sucking air through the suction belt.
 8. The sheet collectingapparatus of claim 2, wherein the suctioning/transporting means is asuction conveyer comprising a breathable suction belt rotating in apredetermined direction and suction boxes disposed inside the suctionbelt for suctioning the sheet on to the front surface of the suctionbelt by sucking air through the suction belt.
 9. The sheet collectingapparatus of claim 3, wherein the suctioning/transporting means is asuction conveyer comprising a breathable suction belt rotating in apredetermined direction and suction boxes disposed inside the suctionbelt for suctioning the sheet on the front surface of the suction beltby suctioning air through the suction belt.
 10. The sheet collectingapparatus of claim 1, wherein the back guide member is formed to have asheet receiving height as a height for receiving the sheet set higherthan the lower edges of the back stoppers
 11. The sheet collectingapparatus of claim 2, wherein the back guide member is formed to have asheet receiving height as a height for receiving the sheet set higherthan the lower edges of the back stoppers.
 12. The sheet collectingapparatus of claim 3, wherein the back guide member is formed to have asheet receiving height as a height for receiving the sheet set higherthan the lower edges of the back stoppers.
 13. The sheet collectingapparatus of claim 2, wherein a sheet receiving height as a height forreceiving the sheet by the back guide member is lower than a positioningheight for positioning the sheet by the side guide members and the frontstopper.
 14. The sheet collecting apparatus of claim 3, wherein a sheetreceiving height as a height for receiving the sheet by the back guidemember is lower than a positioning height for positioning the sheet bythe side guide members and the front stopper.
 15. The sheet collectingapparatus of claim 1, comprising an auxiliary air nozzle disposed belowthe inlet side edge of the suctioning/transporting means from which thesheet is charged for lifting the sheet sucked and transported by thesuctioning/transporting means upward by jetting air upward.
 16. Thesheet collecting apparatus of claim 2, comprising an auxiliary airnozzle disposed below the inlet side edge of the suctioning/transportingmeans from which the sheet is charged for lifting the sheet sucked andtransported by the suctioning/transporting means upward by jetting airupward.
 17. The sheet collecting apparatus of claim 3, comprising anauxiliary air nozzle disposed below the inlet side edge of thesuctioning/transporting means from which the sheet is charged forlifting the sheet sucked and transported by the suctioning/transportingmeans upward by jetting air upward.
 18. The sheet collecting apparatusof claim 4, wherein the front stopper is formed such that the positionthereof can be changed according to the measurement of a sheet to becharged in the charging direction thereof.
 19. The sheet collectingapparatus of claim 7, wherein the front stopper is formed such that theposition thereof can be changed according to the measurement of a sheetto be charged in the charging direction thereof.
 20. The sheetcollecting apparatus of claim 10, wherein the front stopper is formedsuch that the position thereof can be changed according to themeasurement of a sheet to be charged in the charging direction thereof.21. The sheet collecting apparatus of claim 13, wherein the frontstopper is formed such that the position thereof can be changedaccording to the measurement of a sheet to be charged in the chargingdirection thereof.
 22. The sheet collecting apparatus of claim 15,wherein the front stopper is formed such that the position thereof canbe changed according to the measurement of a sheet to be charged in thecharging direction thereof.
 23. A method of collecting a sheet chargedby a charging means along a predetermined direction on a collectingtable of a sheet collecting apparatus in a layer state, the sheetcollecting apparatus comprising the collecting table, asuctioning/transporting means disposed above the collecting table, backstoppers disposed downstream of the collecting table along a transportdirection of the sheet, and a back guide disposed downstream of thecollecting table along the transport direction of the sheet adjacent tothe back stoppers, the method comprising: suctioning the sheet chargedby the charging means by the suctioning/transporting means, transportingthe sheet along the charging direction of the sheet, and releasing thesheet above the collecting table; receiving the sheet released from thesuctioning/transporting means downstream of the collecting table alongthe transport direction of the sheet by the back stoppers; andregulating a position along the transport direction of the sheet, whichis received by the back stoppers, by the back guide member.